The present application relates to lateral power devices.
Note that the points discussed below may reflect the hindsight gained from the disclosed inventions, and are not necessarily admitted to be prior art.
Power MOSFETs are widely used as switching devices in many electronic applications. In order to minimize conduction power loss it is desirable that power MOSFETs for a given breakdown voltage have low specific on-resistance. Specific on-resistance (Rsp) is defined as the on-resistance area product (Ron*A). There is a need for new structures in order to meet the increasing requirement of reduced Rsp for many new applications. Lateral power MOSFET structures are required in many applications that require the monolithic integration of one or more MOSFET in addition to other circuit components.
The present application discloses a number of lateral power semiconductor structures and methods of fabrication utilizing charge balance techniques to achieve high breakdown voltage. The new structures have several advantages over the state of the art devices in particular having low specific on-resistance Rsp, more cost effective and compatible with conventional termination structures such as Field Plates, Guard Rings or Junction Termination Extension (JTE).
The present application teaches, among other innovations, lateral power devices, and methods for operating them, in which charge balancing is implemented in new ways. In a first inventive teaching, the lateral conduction path is laterally flanked by regions of opposite conductivity type which are self-aligned to isolation trenches. In a second inventive teaching, which can be used separately or in synergistic combination with the first teaching, the drain regions are self-isolated. In a third inventive teaching, which can be used separately or in synergistic combination with the first and/or second teachings, the source regions are also isolated from each other. In a fourth inventive teaching, the lateral conduction path is also overlain by an additional region of opposite conductivity type.